Disclosed herein is a seat, and particularly a seat including sensors configured to detect the body potential of an occupant when the occupant is seated.
A configuration has been already known, in which sensors configured to detect the body potential of a seated occupant to monitor the health and wakefulness of the seated occupant are attached to a seat. For example, JP 2009-50679A discloses a configuration in which electrode sensors are embedded in a cover of a backrest of a driver's seat to measure the heart rate of a driver of an automobile.
The above-described electrode sensor is a sensor, i.e., a capacitive coupling sensor, capable of detecting the body potential through clothes of the driver and the cover member of the seat without contacting the skin of the driver. In the configuration of JP 2009-50679A, these sensors can be used to detect a weak signal from the heart of the driver while the driver is seated on the seat. The sensors disclosed in JP 2009-50679A provide an electrocardiographic measurement device suitable for mounting on a vehicle.
The electrostatic capacitance between an electrode sensor and the skin of the subject (such as the driver) is greatly influenced by the detection accuracy of the body potential, and a lower electrostatic capacitance generally results in a lower detection accuracy. Moreover, the space between the skin of the subject and each electrode sensor might change due to, e.g., a change in the posture of the driver and vibration of the vehicle while the vehicle is running. Accordingly, the above-described electrostatic capacitance changes due to such a change in space.
The size of the electrode sensor, particularly the area of a potential detection surface, might be increased to address the above-described problem. However, when the sensors are placed and embedded in the seat, the area of the potential detection surface cannot be easily increased due to installation space limitations.
At the same time, it is important that the quality of the seat, particularly the sense of seating on the seat (i.e., the comfortability on the seat), is maintained.